This invention relates to arm powered and arm steered vehicles, with two steerable front wheels, for the use primarily by paraplegics, for their enjoyment and exercise.
There are in existence a number of designs of arm powered and arm steered vehicles for paraplegics.
One such vehicle has a single front wheel and two rear wheels, and a drive sprocket assembly is mounted to the front steering column (in place of the handlebar) to both steer and drive the front wheel, except the foot pedals for rotating the sprocket have been replaced with appropriate hand grips. Rotating the drive sprocket with the hand grips provides, through a chain and sprocket transmission with a standard 3-speed bicycle hub in the front wheel, power to the steerable front wheel. The use of rotary hand motion for propulsion, where the arms are required to push with one hand and simultaneously pull with the other hand, is not a desirable or efficient means to provide torque to the drive wheel, especially during turning, as it generates unwanted vehicle steering along a serpentine path even while trying to maintain a straight path. Moreover, this propulsion action requires torsional spinal control and related strength, which can be a problem for many paraplegics.
Another vehicle design uses two vertical levers pivoted at their lower ends in front and to each side of the rider's seat and having hand grips at their upper ends. These two levers provide independent propulsion through appropriate power transmission means to a 3-speed hub in each of the two rear wheels, but propulsion only occurs in pulling on the levers. The single front wheel is steered by the rider shifting his weight laterally of a pivotal cycle frame, which through linkage rotates the front wheel's mounting. Again, many potential users would be excluded from using this type drive because of deficient spinal column strength and control.
Another vehicle has two steerable front wheels and a single rear wheel driven via suitable transmission means by pulling on two oppositely oscillating vertical side levers, which again, would exclude many potential users having inadequate deficient spinal column strength and control. Steering is accomplished by swinging these levers to the right or left which though suitable steering linkage turns the two front wheels.